(a) Field
Exemplary embodiments of the invention relate to a scan driving device and a display device including the scan driving device.
(b) Description of the Related Art
An organic light emitting diode display, which is a type of flat panel display, typically displays an image using an organic light emitting diode (“OLED”) that generates light by recombination of electrons and holes. The organic light emitting diode display typically has a high response speed, is driven with low power consumption, and has high luminous efficiency, luminance and viewing angle which receives.
The organic light emitting diode display may be classified into a passive matrix type organic light emitting diode (“PMOLED”) display and an active matrix type organic light emitting diode (“AMOLED”) display according to a method of driving the organic light emitting diode.
The PMOLED display typically includes an anode and a cathode arranged orthogonal to each other and driven by selecting a cathode line and an anode line. The AMOLED display typically includes a thin film transistor and a capacitor integrated in each pixel to maintain a voltage by capacitance.
The AMOLED display generally includes a display device including pixels arranged in a matrix form, a data driving device for transferring a data signal to data lines connected to the pixels, and a scan driving device for transferring a scan signal to scan lines connected to the pixels.
In a driving method of the scan driving device of the AMOLD display, the pixels are selected in a line unit using a plurality of shift registers included in the scan driving device, and the scan signals are sequentially supplied every horizontal period.
Generally, circuit elements constituting the scan driving device are a thin film transistor that functions as a switch. The thin film transistor is operated in a saturation mode by transferring a gate-on-voltage to the thin film transistor. In the scan driving device, a gate electrode voltage applied to the thin film transistor may not be lower than a voltage applied to the scan driving device from the outside, and an output terminal node of the scan driving device may be unstable, such that an operation of a thin film transistor connected to the output terminal node may be substantially unstable.